textproduct: Albany

WHAT HAS CHANGED

Some changes with the timing the transition to rain to snow showers tonight in the wake of the strong cold front.

Slightly higher amounts of snowfall for the southwest Adirondack Fri-Fri night.

Winds were increased in the wake of the clipper and cold front for Sat-Sat night with some gusts in the 35-45 mph range.

KEY MESSAGES

1) Minor river flooding may occur across portions of the southern Adirondacks, Mohawk Valley and the upper Hudson Valley late this afternoon into tomorrow due to the runoff from snow melt, rainfall and any isolated ice jams.

2) A strong cold front will bring showers and isolated to scattered non-severe thunderstorms late this afternoon through tonight, ending as some snow showers on Thursday with some wind gusts around 40 mph for the Mohawk Valley, Capital District, northern Taconics and Berkshires.

3) A clipper system brings moderate to locally heavy snow across portions of the southwest Adirondacks Fri afternoon through Sat morning with below normal temps Saturday afternoon into much of next week. Gusty winds 35-45 mph may occur in the wake of the clippers cold front Sat-Sat night.

DISCUSSION

KEY MESSAGE 1...

A warm front continues to lift back northward of the Mohawk Valley and Capital Region this afternoon. Temps on the south side of the boundary are in the 60s and 70s with 40s and 50s on the north side. A strong mid and upper level trough is approaching from the Upper Midwest and the Upper MS River Valley. A low pressure system is moving along the eastern Great Lakes Region this afternoon into tonight with a prefrontal disturbance ahead of the main cold front. Showers and a few thunderstorms will break out north and west of the Capital Region. PWATs increase to 2 to 4 STDEVs above normal based on the latest NAEFS. The latest NBM 24-hour probs for > 1" of QPF ending 2 AM Thu are 30-55% across the west/southwest Adirondacks with lower probabilities south and east. Rainfall will generally be a quarter to three quarters of inch over the rest of the hydro service area with locally higher amounts from thunderstorms.

Some snow melt with locally moderate to heavy rainfall may produce some minor flooding over or near the western Mohawk Valley, southern Adirondacks and the Upper Hudson River Valley where a Flood Watch remains in effect. Some ice may break up and move causing a jam in the northern streams and rivers. The latest NERFC guidance continues minor flooding forecasts for late tonight or Thu on the Sacandaga River at Hope, the West Canada Creek at Kast Bridge, and also at Delta Dam. Some locations in the Hudson River Basin from Troy northward and the Mettawee at Granville may hit the Alert or Caution stage. River forecasts will continued to be monitored through tomorrow.

KEY MESSAGE 2...

Changeable weather is coming to the forecast area tonight. The mild air mass the past 3-4 days will be gone, as a strong cold front moves through. Widely scattered to scattered thunderstorms will impact the forecast area tonight. The latest HREFS continues to show mean MUCAPEs in the 100-300 J/kg range. O-6 km shear increases to 50-65 KT. The convection should be elevated, but due to the anomalous PWATs some locally heavy rainfall and possibly a few wind gusts could occur if the parcels become sfc based especially closer to I-84. The latest 3-km HRRR has a few clusters or broken lines from I-84 to south of the Capital Region between 6 pm and midnight. The 3-km NAM has a more continuous organized line from the Capital Region/southern VT between 8 pm and midnight. The thunderstorms are expected to be non-severe based on the latest SPC guidance. We have increased PoPs to likely/categorical for the line in this time frame. Temps will fall initially into the 40s and 50s around or shortly after midnight.

Another line of showers moves across the forecast area in the early to mid morning. This will be cold front with strong cold advection, as temps fall into the mid 20s to mid 30s from the Capital Region north and west by sunrise with upper 30s to lower/mid 40s south and east. The mid and upper level trough becomes neutral-negatively tilted over the Northeast late tomorrow morning into the afternoon. Some of the pcpn will transition to snow showers across the region, perhaps even a brief period of ice pellets. Temps will fall into the afternoon and then steady. Snow accums will be a coating to perhaps an inch over the Berkshires and Litchfield hills with less amounts north and west, though a few lake effect snow showers will impact the western Adirondacks with light accums. The post frontal winds with increase from the west to northwest at 12-25 mph with some gusts 30-40 mph. Would not rule out a few isolated gusts 40-45 mph or so over the Mohawk Valley/northern Taconics/Capital Region/Berkshires. The coverage area for wind gusts 46-57 mph is small, so no Wind Advisories at this time unless widespread gusts look achievable with deeper mixing. Temps during the afternoon will be much colder in the 20s to lower 30s over the higher terrain and mid 30s to lower 40s in the major valleys.

KEY MESSAGE 3...

A clipper low and its warm front brings some snow back into the region Fri late morning into Fri night. The isentropic lift increases ahead of the wave with the strongest forcing north and west of the Capital Region. The latest NAM indicates 24-hr probabilities >4" of snow by 2 pm Sat are 40-80% over the southwest Adirondacks...and the >6" probabilities are 35-60% for northern Herkimer and western Hamilton Counties. A Winter Weather Advisory or even a low grade Winter Storm Warning may be needed later in time for the west/southwest Adirondacks. Lighter amounts or snow or rain/snow are expected across the forecast area. The snowfall could impact travel conditions Fri pm-Fri night especially northwest of the Capital Region. After lows in the teens and 20s, expect max temps to rebound into the 30s to lower 40s with some 20s in the Adirondack Park.

The clippers cold front on Sat will allow another surge of cold advection advection as the west/northwest winds increase 15-25 mph with some gusts 35-45 mph once again. The NBM/NBM 90th percentiles winds and gust were blended Sat into Sat night.

A brief mild spell of weather is possible on Monday with more showers and some thunderstorms ahead of an arctic cold front. Behind this boundary temps will plunge 10-15+ degrees below normal for mid-March. It will feel more like mid-Winter Tue-Wed next week. Max temps will struggle to get out the 20s to lower 30s on Tue based on the latest WPC Days 4-7 guidance in our forecast with lows the single digits and teens.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Through 18z Thursday...VFR conditions should mainly prevail for the first 6-9 hours of the TAF period, with just SCT -SHRA and possible brief MVFR conditions. Then as a cold front approaches and moves eastward across the area late this evening into the early overnight hours, there is a high probability of -SHRA with embedded downpours and likely reduction to MVFR conditions. Isolated TSRA possible with the cold front passage, but too sparse to mention in TAFs at this time. The cold front should move through from NW to SE between around 05z-08z. MVFR/VFR conditions expected behind the front, with -SHRA gradually ending. However, there could be renewed SCT -SHRA at KPOU and -SNPL at KPSF after 12z, as a potential weak wave of low pressure develops along the front.

Will mention low level wind shear at all TAF sites from early this evening until the cold front passes through, as a southwest jet of 45-60 kt at 2000 ft AGL moves overhead. The LLWS will be strongest at KPOU/KPSF. Surface winds will be initially south- southeast around 5-12 kt, with gusts around 20 kt developing at KPSF/KALB this afternoon/evening. Winds will shift to the west behind the cold front overnight and will increase to 12-18 kt with gusts of 20-35 kt developing around or just prior to 12z Thursday.

Outlook...

Thursday Night: Moderate Operational Impact. Windy With Gusts To 30 kts. NO SIG WX. Friday: Moderate Operational Impact. Breezy. Chance of RA. Friday Night: Moderate Operational Impact. Breezy. Chance of RA...SN. Saturday: Moderate Operational Impact. Windy With Gusts To 36 kts. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Moderate Operational Impact. Chance of SN. Sunday Night: High Operational Impact. Breezy. Likely RA...SN. Monday: High Operational Impact. Breezy. Definite RA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Flood Watch through Thursday afternoon for NYZ032-033-038-039- 041>043-082-083. MA...None. VT...None.